Plate heat exchanger

ABSTRACT

In a plate heat exchanger, a package of heat transferring plates is kept together between two end plates by means of two or more threaded bolts and nuts in threading engagement therewith. A motor is arranged through an endless drive member, such as a tooth belt or the like, simultaneously to rotate all the bolts or all the nuts. The plate heat exchanger thereby may be rapidly, simply and safely opened and restored for operation in connection with inspection and/or cleaning of the heat transferring plates.

The present invention relates to a plate heat exchanger of the kindcomprising a package of heat transferring plates, two end plates betweenwhich the package of heat transferring plates are kept together, atleast two, preferably at least four, threaded bolts, and nuts or thelike in threading engagement each with one of said bolts, the bolts andnuts being arranged for movement of one of said two end plates towardsor away from the other end plate.

When used for certain applications a plate heat exchanger of this kindmay need to be opended relatively often, e.g. once every day, forinspection and/or cleaning of the heat transferring plates. This meansthat either the above said bolts or the nuts have to be rotated, so thatthe end plates and thus the heat transferring plates may be moved awayfrom each other, often as much as 50 centimeters or more.

Such rotation of the bolts or the nuts--in connection with opening ofthe heat exchanger as well as in connection with restoring of it foroperation--means a heavy, time consuming and not quite simple work. Itis true, particularly in connection with large plate heat exchangers,that electrically or pneumatically operated tools are used for therotation, but a tool of this kind has to be moved often between thedifferent bolts or nuts--particularly at the beginning of an openingoperation and at the end of a restoring operation--in order that thebolts and end plates will not be subjected to all too uneven loads orstresses. In connection with compression of the package of heattransferring plates it is also important that each one of the bolts ornuts is rotated exactly so much that the end plates in their operatingpositions will be situated in parallell with each other. If not so,leakage may come up between the heat transferring plates.

The present invention has for its object to provide an apparatussubstantially facilitating opening of a plate heat exchanger andrestoring of it for operation.

For this purpose it is suggested a plate heat exchanger of the initiallydefined kind, which is characterized by a flexible endless drive member,such as a tooth belt or the like, which partly surrounds and engages byrotational driving engagement each one of said bolts, or each one ofsaid nuts, and a motor in driving engagement with the drive member forsimultaneous rotation of all the bolts or nuts.

By means of such a device the plate heat exchanger may be rapidly andsimply opened to a desired degree and, with the same rapidity andsimplicity, restored for operation after inspection or Cleaning of theheat transferring plates. Only at one place along the package of heattransferring plates the distance between end plates has to be checked inconnection with the compression of the package, because during thiscompression the end plates all the time are kept in parallel with eachother. Through the simultaneous rotation of all the bolts or nuts muchtime can be saved in connection with opening and restoring of the plateheat exchanger. Further, it is made sure thereby that the bolts and theend plates are subjected to a uniform load or stress during the wholecompression of the package of heat transferring plates.

In a preferred embodiment of the invention the bolts extend as drawbolts between the end plates, and the bolts have bolt heads which arearranged to bear directly or indirectly against one of the end plates,said nuts being arranged to bear directly or indirectly against theother end plate. In this embodiment the bolt heads as well as the nutsare preferably coupled to the respective end plates in a way such thatthey are prevented from moving axially away therefrom during operationof the drive member. Hereby, the end plates in connection with openingof the plate heat exchanger may be moved away from each other to adesired degree, while they are kept parallel with each other, just bydriving of the drive member by means of the said motor.

In another embodiment of the invention the bolts are placed between apart of the heat exchanger frame and an end plate movable relative tothis frame part, so that the bolts are subjected to axial pressureforces when pressing the movable end plate towards the other end plate.

Preferably, a gear mechanism is inserted between the motor and the drivemember, so that the motor does not have to exert a too large torquethrough its driving shaft. Either the motor is arranged to drive thedrive member directly through such a gear mechanism, or the motor isarranged to rotate, through the gear mechanism, one of the bolts or oneof the nuts, which is in rotational driving engagement with the drivemember.

One or more guide rollers may be arranged for the drive member, so thatthe latter is caused to surround a larger part than 90° of thecircumference of each bolt head or nut.

The invention is described more in detail in the following withreference to the accompanying drawing, in which

FIG. 1 schematically shows a plate heat exchanger seen from the side,

FIG. 2-4 show details of the heat exchanger according to FIG. 1,

FIG. 5 shows the plate heat exchanger in FIG. 1 seen from the front,i.e. from the right in FIG. 1,

FIG. 6 shows an alternative embodiment of a part of the plate heatexchanger according to the invention,

FIG. 7 shows schematically and in perspective a plate heat exchangeraccording to the invention which is opened for inspection, and

FIG. 8 shows an alternative embodiment of a plate heat exchangeraccording to the invention.

FIG. 1 shows a plate heat exchanger comprising a package of heattransferring plates 1, which are kept together between two end plates 2and 3. The end plate 2 in the following is called the frame plate, andthe end plate 3 is called the pressure plate. The frame plate 2 is partof a frame which for the rest comprises a support column 4 and an upperhorizontal beam 4 and a lower horizontal beam 6. The beams 5 and 6 arefirmly connected with the frame plate 2 and the support column 4 andsupport between themselves the package of heat transferring plates 1 andthe pressure plate 3.

The heat transferring plates 1, which between themselves usually haveflexible edge gaskets and some further gaskets (not shown) for definingflow spaces between the plates for two heat exchange fluids, are kepttogether in this case by four at least partly threaded bolts 7. Thebolts 7 extend between the frame plate 2 and the pressure plate 3 andthrough recesses in the edge portions of these plates. Each bolt 7 has abolt head means 8 (schematically shown) at one of its ends, situated atthe outside of the frame plate 2, and carries a nut 9 on its threadedpart, situated at the outside of the pressure plate 3.

FIG. 2 shows a part of the edge portion of the pressure plate 3, whichedge portion has a recess 10 that opens towards one side. As can beseen, the recess 10 has a substantially cylindrical inner part extendingacross and through the pressure plate 3 at some distance from its edge,and an outer part situated between the cylindrical part and the edge ofthe pressure plate. Said outer part has a width, i.e. a verticalextension, that is somewhat smaller than the diameter of the cylindricalinner part.

A threaded bolt 7 may be inserted into the recess 10 from the side, i.e.from the edge of the pressure plate 3, and then rest in the cylindricalinner part of the recess 10 without rolling out by itself.

FIG. 2 further shows a nut 9 and a plate formed coupling member 11 thatis bent to form an angle of 90°. The coupling member 11 has a firstportion 11a, which has a through hole 12 and which is intended to befirmly connected, with the nut 9 by means of for instance four screws,so that the hole 12 and the hole of the nut will be situated opposite toeach other. Another portion 11b of the coupling member 11 has twosmaller through holes 13, through which two pins 14 protruding from theedge of the pressure plate 3 on respective sides of the recess 10 aresupposed to extend.

The coupling member 11 further has a protrusion 15 arranged to suit intothe outer part of the recess 10, when the coupling member 11 isconnected with the pressure plate 3. The coupling member 11 is intendedto be kept in place at the pressure plate 3 by means of a locking peg 16arranged outside the coupling member portion 11b to extend through holesin the pins 14.

When a nut 9 with its coupling member 11 has been threaded onto a bolt7, the bolt may be inserted into the recess 10 of the pressure plate sothat the pins 14 will extend through the holes 13. The nut 9 thenindirectly, i.e. through the coupling member 11, will bear against theoutside of the pressure plate 3 and be connected with the pressure plate3 in a way such that it may not rotate or move axially relative thereto.

FIG. 3 shows a part of the frame plate 2 and a portion of a bolt 7.Further, it shows in detail and in longitudinal section the bolt headmeans 8 which is only schematically shown in FIG. 1.

Like the pressure plate 3 the frame plate 2 for each bolt 7 has a recessof the same kind as the recess 10 in FIG. 2. Further, for each bolt 7there is a plate formed coupling member 17 bent to form an angle of 90°and having two holes 18 for two pins 19 protruding from the edge of theframe plate 2.

Onto a portion 17a of the coupling member 17, parallel with the frameplate 2, there is welded a sleeve 20 which surrounds the bolt 7 withsome clearance. The inner bearing rings of two angular contact bearings21 and 22 are connected with and surrounds the sleeve 20, whereas theouter bearing rings of the same bearings are connected with a cog-wheel23 surrounding themselves. The bearing 21 abuts axially in one directionagainst shoulders on the sleeve 20 and the cog-wheel 23, respectively,whereas the bearing 22 abuts axially in the other direction against twolocking rings which are connected with the sleeve 20 and the cog-wheel23, respectively. A spacing sleeve 24 keeps the bearings 21 and 22 at adistance from each other.

The cog-wheel 23 has on its circumferential surface cogs 25 and carriesat its part turned away from the frame plate 2 an annular plate 26 whichis coaxial with the bolt 7. As is indicated in FIG. 3, the plate 26 bymeans of screws or the like, indicated by dotted lines 26a through holesin the plate 26, is connected to the cog-wheel 23. Further, the plate26, as indicated by dotted lines 26b in FIG. 3, is firmly connected witha hexagonal bolt head 27, which in turn is firmly connected with the endportion of the bolt 7.

FIG. 4 shows the whole bolt head means 8 seen from the right in FIG. 3.

Upon rotation of a bolt head 27 by means of a tool the bolt 7 will berotated and the nut 9 (FIG. 1) will move axially along the bolt 7. Owingto the fact that the nut 9 is connected with the pressure plate 3 bymeans of the coupling member 11 in the manner described with referenceto FIG. 1 and 2 the pressure plate 3 will be carried by the nut 9 alongthe bolt 7. The axial forces then influencing the bolt 7 will be takenup by the frame plate 2 through the sleeve 20 by the fact that thebearings 21 and 22 are axially fixed relative to the sleeve 20 and thecog-wheel 23, as described previously.

FIG. 5 shows the frame plate 2 seen from the right in FIG. 1. Four bolthead means 8 are shown placed in the corners of an imaginary rectangle.Around all of the bolt head means 8 there extends a flexible tooth belt28, which is in rotational drive engagement with the respectivecog-wheels 23 (FIG. 3) along part of the circumference of eachcog-wheel.

On the frame plate 2 there is mounted an electrical motor 29 whichthrough a gear mechanism housed within a casing 30 is drivinglyconnected with a driving wheel 31. On the frame plate 2 there are alsorotatably mounted three guide rollers 32, 33 and 34 for the tooth belt28.

The tooth belt 28, which may have teeth on both of its sides, extends inthe way that can be seen from FIG. 5, the location of the guide rollers32 and 33 giving as a result that the tooth belt 28 surrounds the largerpart of the driving wheel 31, and the location of the guide roller 34giving as a result that the tooth belt 28 surrounds somewhat more thanone fourth (90°) of the two upper bolt head means 8. As illustrated bymeans of arrows in FIG. 5, the guide roller 34 is adjustable intodifferent positions, so that the tension in the tooth belt 28 can beadjusted when needed.

Upon starting of the motor 29 for operation of the tooth belt 28clock-wise with respect to FIG. 5, all of the bolts 7 of the plate heatexchanger (FIG. 1) will be rotated in one and the same direction, thenuts 9 and the pressure plate 3 moving towards the frame plate 2 andcompressing the package of heat transferring plates 1. Upon simultaneousrotation of the bolts 7 in the opposite direction, the nuts 9 and thepressure plate 3 will, instead, move away from the frame plate 2.

By the simultaneous and uniform rotation of all the bolts 7, and by thefact that the nuts 9 are connected with the pressure plate 3 and thebolt head means 8 are connected with the frame plate 2 in the abovedescribed manner the pressure plate 3 during all of its movement will bemaintained in a position in which it is situated in parallel with theframe plate 2. The package of heat transferring plates will thus becompressed and opened to the same degree along all of its circumference.

It has been described above that the motor 29 and the tooth belt 28 areprovided at the frame plate 2 for rotation of the bolts 7.Alternatively, the motor 29 and the tooth belt 28 may be arranged at thepressure plate 3 and arranged for rotation of the nuts 9. In this case,the nuts 9 would of course be rotatable relative to the pressure plate3, whereas instead the bolt heads 27 would be connected with the frameplate 2 in a manner such that they could not rotate relative thereto.For the rest, like in the above described embodiment of the invention,the nuts 9 as well as the bolt heads 27 would have been connected withthe respective end plates in a manner such that they would not be ableto move axially relative to these respective end plates.

The above described connection of the bolt heads and the nuts with therespective end plates may be accomplished in many different ways withinthe scope of the present invention.

Also, the driving of the tooth belt may be accomplished in manydifferent ways within the scope of the invention. For instance, thetooth belt may be driven by means of a motor the driving shaft of whichis coupled through a gear mechanism to one of the relevant bolt heads orone of the relevant nuts of the heat exchanger. An arrangement of thiskind is schematically illustrated in FIG. 6 which shows a frame plate onwhich a motor is mounted at one of the frame plate corners.

FIG. 7 shows schematically a plate heat exchanger according to theinvention opened for inspection or cleaning of the heat transferringplates. The device for driving of the tooth belt is mounted on the frameplate 2a but is covered by a casing 35. In this case the couplingmembers for axial fixation of the bolt heads relative to the frame plate2 have been designed in a different manner (not shown) than that to beseen from FIG. 3, and the nuts 9 are simply welded onto or connected insome other way directly to the pressure plate 3.

It has been described above that a motor may be mounted on one of theend plates and that a tooth belt may be mounted such that it is inrotational driving engagement with the bolt heads or nuts situated atthis end plate. Within the scope of the invention there is also apossibility that the motor as well as the tooth belt may be mounted on aseparate carrier, which in turn in one way or another is carried by theplate heat exchanger. For instance, a carrier of this kind may besuspended from and be movable along the upper horizontal beam 5 (FIG.1). In a case like this the tooth belt may extend around and be inrotational driving engagement with a number of rotatable sleeves, whichare arranged and designed such that upon movement of the carrier alongthe beam 5 they may be brought into engagement each with one of the nuts9. A unit designed in this manner may be situated close to thesupporting column 4 when not in use.

Instead of a tooth belt any kind of endless drive member, such as adrive chain or the like, may of course be used.

FIG. 8 shows a plate heat exchanger according to an alternativeembodiment of the invention. Parts of this plate heat exchanger whichcorrespond to parts of the heat exchanger according to FIG. 1-7 have thesame reference numerals but with the additon of the letter A.

As can be seen from FIG. 8 the bolts 7A extend from the bolt head means8A, arranged at the pressure plate to and through holes in extensions 36of the support column 4A. Each of the bolt head means 8A is fixed to thepressure plate 3A, so that the bolts 7A can not rotate or move axiallyrelative to the pressure plate 3A.

At the extension 36 of the support column 4A the nuts 9A are inthreading engagement with the end portions of the bolts 7A. The nuts 9Aare rotatable but axially fixed relative to the extensions 36. Hereby,upon operation of the tooth belt 28A by means of the motor 29A, i.e.upon rotation of the nuts 9A, the bolts 7A will be moved axially so thatthe pressure plate 3A moves towards or away from the support column 4A.In other words, by means of the motor 29A the pressure plate 3A may becaused to compress the package of heat transferring plates 1A againstthe frame plate 2A or to open the plate package for inspection and/orcleaning of the heat transferring plates.

I claim:
 1. A plate heat exchanger comprising a package of heattransferring plates (1),two end plates (2, 3) between which the packageof heat transferring plates (1) is kept together, at least two threadedbolts (7), said bolts extending between the end plates (2, 3) and havingbolt heads (27) arranged to bear directly or indirectly against one (2)of the end plates, a plurality of nuts (9), each in threaded engagementwith one of said bolts (7) and arranged to bear directly or indirectlyagainst the other end plate (3), the bolts (7) and nuts (9) beingarranged for movement of one of said two end plates toward or away fromthe other, said heat exchanger further comprising a flexible endlessdrive member (28) partly surrounding and engaging by rotational drivingengagement each of said bolts (7) or each of said nuts (9), and a motor(29) in driving engagement with the drive member (28) for simultaneousrotation of all the bolts (7) or nuts (9), said bolt heads (27) and saidnuts (9) being coupled to their respective end plates (2, 3) in a mannersuch that they are prevented from moving axially away from theirrespective end plates (2, 3) upon operation of the drive member (28). 2.A plate heat exchanger according to claim 1, in which each bolt head(27), or nut (9), which is not in engagement with the drive member (28),is coupled to its end plate in a manner such that it is prevented fromrotating upon operation of the drive member (28).
 3. A plate heatexchanger according to claim 1, in which a friction reducing bearing(21,22) is arranged between each bolt head (27), or nut (9), which is indriving engagement with the drive member (28), and the relevant endplate.
 4. A plate heat exchanger according to claim 1, in which saidmotor (29) is arranged to drive the drive member (28) through one of thebolts (7) or one of the nuts (9).
 5. A plate heat exchanger according toclaim 1, in which a gear mechanism (30) is coupled between the motor(29) and the driving member (28).
 6. A plate heat exchanger according toclaim 1, in whichthe drive member (28) extends around parts of at leastfour bolts (7), or nuts (9), situated in the corners of an imaginaryrectangle, at least one guide roller (24) is arranged for the drivemember (28), and the drive member (28) extends around part of the guideroller (24) in a way such that it is in driving engagement with at leasttwo bolts (7), or nuts (9), along more than one fourth (90°) of theirrespective circumferences.
 7. A plate heat exchanger according to claim1, in which the motor (29) and the drive member (28) are mounted on theplate heat exchanger.
 8. A plate heat exchanger comprisinga package ofheat transferring plates (1), two end plates (2, 3) between which thepackage of heat transferring plates (1) is kept together, at least twothreaded bolts (7), said bolts extending between the end plates (2, 3)and having bolt heads (27) arranged to bear directly or indirectlyagainst one (2) of the end plates, a plurality of nuts (9), each inthreaded engagement with one of said bolts and arranged to bear directlyor indirectly against the other end plate (3), the bolts (7) and nuts(9) being arranged for movement of one of said two end plates toward oraway from the other, said heat exchanger further comprising a flexibleendless drive member (28) partly surrounding and engaging by rotationaldriving engagement each of said bolts (7) or each of said nuts (9), amotor (29) in driving engagement with the drive member (28) forsimultaneous rotation of all the bolts (7) or nuts (9), and a frictionreducing bearing (21, 22) arranged between each bolt head (27), or nut(9), which is in driving engagement with the drive member (28), and therelevant end plate.
 9. A plate heat exchanger comprisinga package ofheat transferring plates (1), two end plates (2, 3) between which thepackage of heat transferring plates (1) is kept together, at least twothreaded bolts (7) a plurality of nuts (9) each in threaded engagementwith one of said bolts, the bolts (7) and nuts (9) being arranged formovement of one of said two end plates toward or away from the other,said heat exchanger further comprising a flexible endless drive member(28) which partly surrounds and engages by rotational driving engagementeach of said bolts (7) or each of said nuts (9), and a motor (29)arranged to drive said drive member (28) through one of said bolts (7)or one of said nuts (9) for simultaneous rotation of all of said bolts(7) or nuts (9).
 10. A plate heat exchanger comprisinga package of heattransferring plates (1A), two end plates (2A, 3A) between which thepackage of heat transferring plates (1A) is kept together, at least twothreaded bolts (7A) a plurality of nuts (9A) each in threaded engagementwith one of said bolts, the bolts (7A) and nuts (9A) being arranged formovement of one of said two end plates toward or away from the other,said heat exchanger further comprising a flexible endless drive member(28A) which partly surrounds and engages by rotational drivingengagement each of said bolts (7A) or each of said nuts (9A), a motor(29A) in driving engagement with the drive member (28A) for simultaneousrotation of all the bolts (7A) or nuts (9A), and a frame (4A-6A) forcarrying the heat transferring plates (1A) and the end plates (2A-3A),one (2A) of the end plates being fixed and the other (3A) being movablewith relation to said frame, said bolts (7A) being arranged between theframe (4A-6A) and the movable end plate (3A) and arranged to press saidmovable end plate (3A) towards the other end plate (2A) and thereby tobe subjected to axial pressure forces.
 11. A plate heat exchangercomprisinga package of heat transferring plates (1), two end plates (2,3) between which the package of heat transferring plates (1) is kepttogether, at least two threaded bolts (7), a plurality of nuts (9) eachin threaded engagement with one of said bolts, the bolts (7) and nuts(9) being arranged for movement of one of said two end plates toward oraway from the other, said heat exchanger further comprising a flexibleendless drive member (28) which partly surrounds and engages byrotational driving engagement each of said bolts (7) or each of saidnuts (9), a motor (29) in driving engagement with the drive member (28)for simultaneous rotation of all the bolts (7) or nuts (9), and at leastone guide roller for the drive member, said drive member extendingaround parts of at least four bolts (7) or nuts (9) situated in thecorners of an imaginary rectangle, and around part of the guide roller(24) in such a way that it is in driving engagement with at least twobolts (7) or nuts (9) along more than one fourth (90°) of theircircumference.